Perhaps the broad interest in and the importance placed on social media by industry, policymakers, researchers, and others is based on the assumption that social media activity must impact individual behavior, or at least be a reflection of behavior. However, there is little or no empirical research explicitly examining whether or not this is true - does social media impact individual consumer behavior (or at least reflect it)? The topic of this proposal - electronic cigarettes (or e-cigarettes) - is ideal for addressing this question. These battery-powered nicotine delivery devices have emerged in the U.S. market in the past five years and have had a strong online presence, including within social media. Within the context of varied levels of tobacco control across states and a range of e-cigarette advertising, there were a dramatic increases in awareness (40.9% in 2010 to 75.4% in 2012) and use of e-cigarettes (3.3% ever use in 2010 to 8.1% in 2012). Drawing from the Socio Ecological Model and Diffusion of Innovation, contextual factors such as social influence, advertising, and public policy play an important role in tobacco use and rate of adoption. Using this foundation, we will examine specific tobacco control policies (per the American Lung Association's State of Tobacco Control) and e-cigarette advertising (per Competitrack Advertising Data) in relation to social media activity, specifically Twitter activity (volume, sentiment, and source from Gnip). We will also examine these greater contextual factors (tobacco control activity, e-cigarette advertising, Twitter activity) in relation to e-cigarette purchases, per the Nielsen Consumer Panel data, which records household purchases at the Universal Product Code (UPC) level among over 60,000 panelists beginning in 2004. We will triangulate these data sets through ZIP codes and use data from January 2011 to December 2013. Our specific aims are to: 1) examine the association between e-cigarette Twitter activity (volume, sentiment, source) and e-cigarette purchasing behavior (volume) per the Nielsen Consumer Panel data; 2) examine tobacco control policies (prevention, cessation, tax, smoke- free policy) and e-cigarette advertising (traditional, new media) in relation to e-cigarette Twitte activity; and 3) model e-cigarette purchasing through tobacco control policies, e-cigarette advertising, and e-cigarette Twitter activity over time and across states. The unique triangulation of these multilevel data will yield timely and important information given the emergence of e-cigarettes; the increased use of new and social media to promote e-cigarettes, other tobacco products, and substance use more broadly; and the need to understand the impact of policy and advertising on social media activity and ultimately the use of e-cigarettes. Examining the aforementioned aims of this R21 will establish whether these associations exist and provide data for a larger study including online sales of e-cigarettes, a larger range of advertising effors, and tobacco control activities within counties or cities to further extrapolate and contextualize the impact of social media on e- cigarette use. This may provide a basis for examination of similar factors related to use of other substances.